This disclosure relates to voltage regulators and more specifically, to a hysteretic mode synchronous buck voltage regulator.
A voltage regulator converts an input voltage to a regulated output voltage. Although there are many types and applications for voltage regulators, one such type is a switching, DC-to-DC, step-down voltage regulator, or "buck" regulator. The switching regulator is often chosen due to its small size and efficiency. An example of a typical application is a battery-powered electronic device such as a portable computer. In an example such as this, a voltage regulator is required to provide a predetermined and constant output voltage to a load from an often-fluctuating input voltage source, the battery.
A hysteretic-mode voltage regulator works by regulating the output voltage according to a particular hysteresis level or output voltage ripple. A hysteretic controller in the voltage regulator maintains the output voltage within a hysteresis band centered about the internal reference voltage. The level of hysteresis or ripple is fixed through the entire load range of the voltage regulator.
In a switching regulator, the field-effect transistors (FETs) switch on and off to maintain a certain switching frequency. During this switching time, the transistors enter a linear region where much power is dissipated because the FETs are sourcing current.